1. Field of the Invention
The present invention relates to a stator, and more particularly, to a stator core constructed in a structure in which stress and spring back of the stator core are minimized when a stator is manufactured in a spiral fashion, whereby workability is improved.
2. Discussion of the Related Art
Based on the drive mode thereof, a motor may be classified as an indirect connection type motor which indirectly transmits a drive force to an object to be rotated using a pulley and belt or a direct connection type motor, such as a brushless direct current (BLDC) motor, in which a rotor of the motor is directly connected to an object to be rotated such that a drive force from the motor is directly transmitted to the object.
In the indirect connection type motor, the drive force of which is not directly transmitted to the object but indirectly transmitted to the object via a belt wound on a pulley of the motor or the object, however, energy loss occurs, and a large noise is generated, during the transmission of the drive force.
For this reason, there has been increasingly used the direct connection type motor, i.e., the BLDC motor, which solves the problems caused from the indirect connection type motor.
The BLDC motor includes a rotor directly connected to an object to be rotated for transmitting a drive force to the object and a stator for generating a magnetic force, when electric current is supplied to the stator, to rotate the rotor using an attractive force and a repulsive force between the stator and the rotor.
The stator may be manufactured by stacking a plurality of blanked cores or by stacking a core in a spiral fashion.
For the stator manufactured by stacking the blanked cores, a large amount of core scrap is generated during blanking the cores, whereby material costs are increased. For the stator manufactured by stacking the core in the spiral fashion, on the other hand, a base material is stacked in the spiral fashion, whereby the generation of core scrap is minimized, and therefore, the increase of material costs is minimized.
Hereinafter, a conventional stator manufactured by stacking a core in a spiral fashion will be described with reference to FIGS. 1 and 2.
FIG. 1 is a perspective view illustrating a conventional stator core stacked in a spiral fashion, and FIG. 2 is a plan view of the conventional stator core after the stacking of the stator core is completed.
As shown in FIGS. 1 and 2, the stator core includes a yoke 1 having guide holes 1a, into which guide pins of a winding apparatus (not shown) are inserted, and a plurality of teeth 3 protruding from the outside of the yoke 1 such that a coil is wound on the teeth 3.
When winding the stator core, large stress is generated at the inside of the yoke 1. In order to reduce the stress, as shown in FIGS. 1 and 2, notches 5 are formed at the inside of the yoke 1.
However, the stator core with the above-stated construction has the following problems.
First, as shown in FIGS. 1 and 2, the guide holes 1a, formed in the stator core, are arranged in a one-to-one correspondence to the teeth 3.
In other words, the guide holes 1a are not formed between the respective teeth 3. As a result, when the stator core is wound while the guide pins of the winding apparatus are sequentially inserted into the guide holes 1a of the stator core, it is not possible to maximize a support force of the stator core that is supported by the guide pins of the winding apparatus.
Consequently, the stator core does not minimize spring back generated due to the restoring force of the stator core.
Secondly, the number of the notches 5 formed between the respective teeth 3 is one, and therefore, it is not possible to minimize stress generated at the inside of the yoke 1 when winding the stator core.